SSI may refer to any of the following:
1. Short for Small-Scale Integration, SSI is a chip architecture that has fewer than 30 transistors per chip.
2. When referring to an Internet web page SSI is short for Server Side Include and is a file that includes Apache executable server code. For example, a SHTML file extension is an HTML file that includes instructions that need to be executed by a server. It is important to realize that you do not need to rename your files to a .shtml for server side includes to be supported. You can also use the xBitHack in the .htaccess to execute any file with an executable file permission.
Once a file has been renamed to a .shtml or if the xBitHack is enabled and the file is set to executable to include something from the server add the below line into the file.
<!--#echo var="DATE_LOCAL" -->
If server side includes are properly enabled when opening the web page in the browser it should display the local date and time.
After verifying that SSI works you can then include any file using code similar to the example below. In the example below, we're executing a perl script called example.pl in the cgi-bin directory.
If something goes wrong when attempting to execute the SSI file You'll get an error occurred while processing this directive error message. This error message is often encountered either because the path pointing to the included file is wrong or if including a script it is generating an error. To resolve this issue make sure that the included file exists and if a script that it can be accessed through a web page without any errors.